Sudden Death in the Young (SDY) is a tragic event with longstanding impact on families and communities. Although the causes of SDY are myriad, sudden unexpected infant death (SUID), sudden cardiac death and sudden unexpected death in epilepsy (SUDEP) are three examples that have inspired public health efforts at prevention. Yet fundamental gaps in knowledge about incidence, mechanisms, and risk factors for SDY limit the identification of effective prevention efforts. The Sudden Death in the Young (SDY) Case Registry is a collaboration between the National Institutes of Health (the National Heart, Lung, and Blood Institute (NHLBI) and the National Institute of Neurological Disorders and Stroke(NINDS)) and the Centers for Disease Control and Prevention (CDC).